[PATCH 6.1 2/2] io_uring/io-wq: inherit cpuset of cgroup in io worker

[Felix Moessbauer]

commit 84eacf177faa605853c58e5b1c0d9544b88c16fd upstream.

The io worker threads are userland threads that just never exit to the
userland. By that, they are also assigned to a cgroup (the group of the
creating task).

When creating a new io worker, this worker should inherit the cpuset
of the cgroup.

Fixes: da64d6db3bd3 ("io_uring: One wqe per wq")
Signed-off-by: Felix Moessbauer <felix.moessbauer@xxxxxxxxxxx>
---
 io_uring/io-wq.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/io_uring/io-wq.c b/io_uring/io-wq.c
index c74bcc8d2f06..04265bf8d319 100644
--- a/io_uring/io-wq.c
+++ b/io_uring/io-wq.c
@@ -1157,6 +1157,7 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
 {
 	int ret, node, i;
 	struct io_wq *wq;
+	cpumask_var_t allowed_mask;
 
 	if (WARN_ON_ONCE(!data->free_work || !data->do_work))
 		return ERR_PTR(-EINVAL);
@@ -1176,6 +1177,9 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
 	wq->do_work = data->do_work;
 
 	ret = -ENOMEM;
+	if (!alloc_cpumask_var(&allowed_mask, GFP_KERNEL))
+		goto err;
+	cpuset_cpus_allowed(current, allowed_mask);
 	for_each_node(node) {
 		struct io_wqe *wqe;
 		int alloc_node = node;
@@ -1188,7 +1192,8 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
 		wq->wqes[node] = wqe;
 		if (!alloc_cpumask_var(&wqe->cpu_mask, GFP_KERNEL))
 			goto err;
-		cpumask_copy(wqe->cpu_mask, cpumask_of_node(node));
+		if (!cpumask_and(wqe->cpu_mask, cpumask_of_node(node), allowed_mask))
+			cpumask_copy(wqe->cpu_mask, allowed_mask);
 		wqe->node = alloc_node;
 		wqe->acct[IO_WQ_ACCT_BOUND].max_workers = bounded;
 		wqe->acct[IO_WQ_ACCT_UNBOUND].max_workers =
@@ -1222,6 +1227,7 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
 		free_cpumask_var(wq->wqes[node]->cpu_mask);
 		kfree(wq->wqes[node]);
 	}
+	free_cpumask_var(allowed_mask);
 err_wq:
 	kfree(wq);
 	return ERR_PTR(ret);
-- 
2.39.2